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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - compile-time explosion with assumes at -O2 and -Os"
href="https://bugs.llvm.org/show_bug.cgi?id=49541">49541</a>
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<th>Summary</th>
<td>compile-time explosion with assumes at -O2 and -Os
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Scalar Optimizations
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
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<th>Reporter</th>
<td>haoxintu@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
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<pre>Hi, all.
This code, small.c, is a valid program but makes Clang trunk hung on at compile
time at -O2 and -Os. Note that this issue also occurs in recently released
versions of clang, e.g., clang-10, clang-11.
$cat small.c
#include <stdint.h>
int a;
void b(int c) {
int32_t *d = a;
uint64_t e;
int8_t f = 4;
uint16_t g;
if (0)
j:
if (e <= (*d *= a))
goto j;
i:
if (c ? g %= f : *d)
goto i;
goto j;
}
$clang -O2 -w small.c (or -Os)
//endless compiling
$clang -v
clang version 13.0.0 (<a href="https://github.com/llvm/llvm-project">https://github.com/llvm/llvm-project</a>
590ac0a26af4c9f63d5564be8c13b12d409a7fd9)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir:
/home/haoxin/haoxin-data/dut-research/compilers/llvm-project/build-20210310/bin
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/7.5.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/8
Candidate multilib: .;@m64
Selected multilib: .;@m64
Thanks,
Haoxin</pre>
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